Screw driver



Oct. 22, 1940. M. A WEST ET AL 2,218,631

SCREW DRIVER Filed Aug. 1, 1939 2 Sheets-Shet 1 Fig. 4

hwenfors Maxwel/ ,4. W632 George 5. Wesf By 141 w.

,4 Hal /5 eys Oct. 22, 1940. M. A. was-r ET AL S CREW DRIVER Filed Aug. 1, 1959 2 Sheets-Sheet 2 Fig 7 SS s rWW. m s o y 6 n n S .r nww m xo M Patented Oct. 22,

UNITED STATES PATENT oi-P cs SCREW DRIVER Application August 1, l9 39,s'erial No. 287,773

8 Claims.

This invention relates to screw drivers 01' various types, both manual and machine-operated, and including drivers for the common singleslotted screw. More particularly, however, this invention relates to-drive'rs designed for recessedhead screws of the types which have, in more recent years, been introduced into the market in partial substitution of the common screw. Especially this invention relates to a driver for the improved screw described in our co-pending application, Serial No. 287,772.

When driving a screw into place, it is not always possible to keep the axis of the screw driver in alignment with the axis oi? the screw. In such cases, the tip or bit of the driver, or the chisel end of the ordinary screw driver, is liable to escape from the slot or recess in the head of the screw, marring the slot or reaming the screwhead recess. Furthermore, when it is desired to drive a screw in such a location that the axis of the screw driver is required to be held out of alignment with the proper axis of the screw, this is .very often impossible when rigid drivers, now commonly in use, are employed.

An object of this invention is to provide a driver which will efiectively drive a screw under the conditions above-mentioned. This object we accomplish by making our driver with a shank and a separate bit, so arranged that their axes will be permitted slight movement out of alignment with each other, but will nevertheless be normally held in alignment.

Another object of this invention is to provide a screw driver in which the bit, or driving tip may be moved out of such alignment with the main axis of the driver without requiring any sacrifice of strength in the driver.

A further object is to provide a driver in which the bit or point can be removed and replaced.

without difliculty.

A still further object oi. this invention is to provide such a driver which will be simple in construction and inexpensive to manufacture.

The manner in which we attain these and other objects in our improved screw driver will be brought out in the following description with reference to the accompanying drawings.

In the drawings: t

Figure 1 is-a perspective view of a preferred embodiment of our invention;

Figure 2 is an enlarged perspective view oi. the end of the shank with the screw driver bit removed and a portion of the coil spring broken away to reveal certain details oi! construction;

Figure 3 is a similar view of the driving bit;

bit shown in elevation;

Figure 4 is a perspective view 0! a section 01' milled bar stock from which the screw driver bits may be made;

Figure 5 is an enlarged elevation showing our improved screw driver in operable position in a 5 screw;

Figure 6 is a corresponding vertical medial section of parts of the screw and driver with the Figure 7 is a perspective view of a modified bit. 10

Referring first to the preferred form of our invention illustrated in Figures 1 to 5, a metal rod or shank I0 is formed with a rounded nose I0, which is bifurcated by two slots, (Fig. 2).

These slots intersect the axis of the shank I0 and 1'3" intersect at right angles to each other thus providing two pairs of aligned slots II and II and.

I2 and I 2 for receivingthe wings l3, I3 and I4, I4, respectively of a screw driving attachment or bit such as that shown in Figure 3 and designated I5. The widthof the slots II, II', I2 and I2 is made sufficiently in excess of the thickness of the wings of the bit to allow the wings to shift laterally, to a certain extent, in theslots, as illustrated in Figure 5. 25

The slots II, II, I2 and I2 extend a substantial distance along the shank III, so as to aiford ample bearing area between the bifurcated shank and the wings of the bit I5, and the pairs of slots II, II and I2, I2 terminate in flat end walls. I8 and I1 respectively, which lie in a plane perpendicular to the axis of the shank l0. These end walls I6 and I1 provide fiatbearing surfaces for the inserted ends of the wings, I3, I3 and I4, ll, of the bit. These ends of the wings are curved downwardly, from their common point of intersection, as indicated at a: in Fig. 3 and shown more clearly in Figure 6. so that the bit may be moved in the slots and the, shank I0 will bear on the ends of the bit regardless of the relative alignment or misalignment of the shank and bit. I In other words, the screw driving bit I5 may rock and slide on the end walls I8 and I! of the slots when the shank III is swung out of alignment as illustrated in Figures 5 and 6. A removable dowel or pin l8 tightly fitted in a hole in the rounded nose I0 of the shank (Figures 1 and 2) and passed t ough a larger hole I9 in the bit, (Figure 3) reta the bit in the shank while at the same time permitting it to move laterally so as explained.

The hole I9 is made of sufllcient size to permit the top of the bit always to bear against the ends of the slots of the shank when the shankispressed down on the bit, when driving a screw, i'or'ex as ample as shown in Figure 6, thereby preventing anystrain tobebornebythepin ll. Thisis an important feature in our invention.

In order to cause the bit to normally be positioned in the shank in alignment with the shank axis and to cause the bit to rettu'n to such alignment immediately upon being released from a misaligned screw, we provide a coiled spring 20 in a peripheral groove 2| (Figure 2) in the shank in such manner that the coiled spring Ill encompasses a substantial portion 01' the' slots ll,

ll, I2 and l2 and bears on the driver wings of coils will resume their normal position and thus bring the bit back into axial alignment with the shank. This is another important feature of our invention. It will be apparent from Figs. 1, 2, 3 and 5, that the bit' II! can easily be removed from the shank II) by merely withdrawing the pin it. Thus. shouldthe bit become damaged or the tip worn, or should a bit with a, diflerently-shaped tip be required. thebit can readily be' changed.

The detachable bit .l5, illustrated in Figures 1, 3, 5 and ilms thetipland driving win 'siormed slmilarl liio. t e ,sll t'q a l driv r mtendedior use with thqimprovedrecessedrhead'scmw shown in ourjcmpendingjapplicatlcn, Serial No... 2 87.772.- such screw, b ing .tlm irli' 1n Flfl tesit andfi. and the wines.;. lttnd 13, are adant dtapntint the m an slotioiffihe scr w-and thenarrcw r" and sli htly thinner ings... I; and u. .e rage the "spine slots .oi, th s rew irecess as in our said tic-pending application: Bits with diflerentlyjshapediipa suitable j for other typw of sc e rccc sealgan of course be used in the same-way It is characteristic of ane ia; or recessed screws that the more nearly'rlth'e driver can be held to .co-axial ali nment with the screw, the lelsswili be the tendency toward fracture or the screw head and abra ion or the driving tocl and the reateriwill-be the emciency oi the driver.

' From Figures 5 and 6 it will beapwlrent how the operative end or bit of our improved driver, with the joint near the end, compensatesfor misalignmerit between the driver and screw, or, in other words, allows the bit to be properly seated in the screw recess, even though the shank. of the driver occupies a misaligned position. This important feature of our invention would apply to either a manually operated driver, in which case the shank I0 is securely set in a handle 23 (Fig. 1), or to a power driver, the shank lll being then held in the chuck or the rotary machine. The fact that the bit may be readily removed irorn theshank by simply withdrawing the pin l8,is of particular importance in connection withthe efficiency of power drivers becauseof the moreor v ,be made in any desiredform to coincide with the less frequent replacement because of wear of the driver or because of changes in sizeoi screws tobedriven.

As previously indicated, that portion oi the bit which projects from the driver shank may particular type of screw tobedriven. ii the driver is to be used for ordinarysingle-slotted screws the bit may be made int-he form, illus- ,trated in Figure 7 with one pairoialigned wings 21, tapered to a wedge point similar to that of a conventional screw driver', 'and the other pair of wings, as 29, merged into this wedge point substantially as shown. The driving bit for slotted screws thus formed may be provided with an enlarged hole 30 pin I8.

Various types of detachable bitswith two-pairs of wings, such as those illustrated, we have tound can be manufactured very economically in they for receiving the following manner? A long bar of metal, such that shown in part in Figure 4 and designated M, is machinedor otherwise iormedto the 'exact widths and thicknesses of the bits required, {then shaped atuniform intervals to make the curved edges of the wings. The bar isthen out into in-ij dividual driver bits. B y this method, the separate machining operations usually required are substantially reduced.

Since, in the operation 01 driving-almost any type of screW,,.considerab-le pressure is'required tone exerted on .the head thereof resultingin.

in our-driver with two pairs of wings and td make the shank correspondingly "with slots inter.-

secting on the andarranged at right angles to each-other,.it would. nevertheless. be,

possible to carry out qur'invention byrusing a bit iormed from a. single v itraight piece oi. metal, thus without, arm; spines,? and, similarly,

have only a single ,slot in the shank, su h an extending through the axis 01 the preferably 'Other modifications in the form, shape, and construction of the bit with corresponding moat fications in the shank will be possible with ut departing from the principle of our inventiorn r We claim:

l. A screw driver comprising, a shank secured at one end to a handle, apair oi intersecting slots in the otherrend of said shank extending a short distance-longitudinally in said shank, a groove extending around-said shank crossing the edges. oi said slots, v-a bit adapted to beinserted' in said slots, the inserted and of said bit having ribs corresponding to saidslots, but the thickness of said ribs being less than the width 01 said slots to permit the axis of said bit .to be moved out of alinement with the axis of said shank, meansior holding said bit in said shank,- said means including a transversely extending pin in sorted portion of said bit, said hole-being or a diameter larger than that of said pin-and a spring located in said groove, engaging the edges idribfi- A 2. A4 screwdriver comprising, a shank secured at: one-endutoa handle, a pairoi intersecting slots in. the other end oi said shank extending a short distance longitudinallyin said-shank, said slots intersecting each' other at right angles, a

.said shank extending through a hole in the inrecess extending around said shank crossing the edges or said slots and in aplane perpendicular to the planes oi said slots, a bit adapted to be inserted in said slots, the inserted end of said bit having ribs corresponding to'said'slots, but the thickness of saidribs being less than the width or said slots to permit the axis of said bit to be moved out-of alin'ement with the axis of said shank, means for holding said bit in said shank, and means for normally holding said bit in alinement with the axis of said shank, said latter mentioned means comprising a spring on said shank in said recess engaging the edges of the inserted portion of said bit.

3. The combination described in claim 2 with the top of the inserted end of said bit being curved to permit said bit to rock and slide freely on the ends of said slots in said shank.

4. In a screw driver, a shank, a pair oi intersecting slots in the end of said shank extending a short distance longitudinally in said shank, said slots intersecting each other at right angles, a recess extending around said shank crossing the edges of said slots, a bit adapted to be inserted in said slots, the inserted end of said bit having ribs corresponding to said slots, but the thickness of said ribs being less than the width of said slots to permit the axis of said bit to be moved out of alinement with the axis of said shank, means for holding said bit in said slots, said means including a transversely extending pin in said shank extending through an enlarged hole in the inserted portion of said bit, and means for normally holding said bit in alinement with the axis of said shank, said latter mentioned means including a spring in said recess of said shank engaging the edges of the inserted portion of said bit.

5. The combination described in claim 4, with the top of the inserted end of said bit being curved to permit said bit to rock and slide freely on the ends of said slots in said shank.

6. In a screw driver, a shank, a slot in the end of said shank extending a short distance longitudinally in said shank, a recess extending around said shank crossing the edges of said slot, a bit adapted to be inserted in said slot, the inserted portion of said bit being of less thickness than the width of said slot to permit the axis of said bit to be moved out of alinement with the axis of said shank, means for holding said bit in said shank, said means including a transversely extending pin in said shank extending through an enlarged hole in the inserted portion of said bit, and means for normally holding said bit in alinement with the axis of said shank, said latter mentioned means comprising a spring in said recessof said shank engaging the edges of the inserted portion of said bit, the top of the inserted end of said bit being curved to permit said bit to rock and slide freely on the end of said slot insaid shank. I

7. In a screw driver, a shank, a pair of intersecting slots in the end of said shank extending a short distance longitudinally in said shank, a bit adapted to be inserted in said slots, the inserted end of said bit having ribs corresponding to said slots, but the thickness of said ribs being less than the width of said slots to permit the axis of said bit to be moved out of alinement with the axis of said shank, means for holding said bit in said shank, said means including a transversely extending pin in said shank extending through an enlarged hole in the inserted portion of said bit.

8. In a screw driver, a shank, a pair of longitudinal intersecting slots in the end of said shank, a bit inserted in said slots, the inserted end of said bit having longitudinally extending radial ribs corresponding to said slots, the thickness of said ribs being less than the width of said slots to permit the axis of said bit to be moved out of alinement with the axis of said shank but the walls of said slots limiting such movementout of alinement, the top of the inserted end of said bit being curved to permit said bit to rock and slide freely on the ends of said slots in said shank, an enlarged hole in the inserted portion of said bit, and a transversely-extending pin in said shank extending through said hole in said bit for retaining said bit in said shank.

MAXWELL A. WEST. GEORGE E. WEST. 

